锆英石加入量对低碳镁碳砖抗剥落性能的影响

为了提高VOD钢包用低碳镁碳砖的抗剥落性能，以粒度为5～3、3～1、<1和<0.088 mm的电熔镁砂，粒度<0.15 mm的天然鳞片石墨，粒度<0.045 mm的金属铝粉和粒度<0.05 mm的锆英石粉为主要原料，热固性酚醛树脂为结合剂，制备了低碳镁碳砖，研究了锆英石加入量(加入质量分数分别为0、1%、2%、5%)对低碳镁碳砖抗剥落性能的影响。结果表明：1)添加1%(w)锆英石试样的高温抗折强度、抗热震性、抗氧化性及抗渣性均达到最大，说明锆英石的加入有助于提高低碳镁碳砖的抗剥落性能。2)添加锆英石的试样经1 400℃埋碳加热0.5 h后，基质中有针状、连续片状空间结构的阿隆(AlON)以及片状氧化铝-氧化锆复合物生成，且通过钉扎增韧以及颗粒增韧提高了高温力学性能和抗热震性。3)加入过量的锆英石会导致氧化锆生成量明显增加，其高温下的体积变化使基质中微裂纹聚集，造成试样的抗剥落性能大幅下降。     

引入碳纤维对低碳镁碳砖性能的影响

为了解决低碳镁碳砖使用过程中容易出现的热剥落问题,在w(C)≈6%的低碳镁碳砖中加入尺寸约为Φ10 mm×20 mm的碳纤维,并研究碳纤维加入量(w)分别为0.25%和0.5%时,试样经180℃保温10 h固化后以及经1 000和1 600℃保温3 h埋炭热处理后的强度、弹性模量、抗热震性以及热膨胀等性能的变化。结果表明:与未添加碳纤维材料相比,添加0.25%(w)碳纤维时,试样的抗氧化性和经不同温度处理后的强度均明显提高,常温弹性模量和高温线膨胀率有所降低,抗热震性能有明显改善;但碳纤维含量增加至0.5%(w)时,试样的抗氧化性和经不同温度埋炭热处理后的强度均下降,弹性模量和高温线膨胀率变化不大,但抗热震性能有下降的趋势。综合考虑,添加0.25%(w)碳纤维的低碳镁碳砖综合性能最佳。     

不同铝基原料对MgO-Al-C材料性能和显微结构的影响

以烧结镁砂骨料、电熔镁砂细粉、Al粉、N220炭黑为原料,酚醛树脂为结合剂,制备MgO-Al-C材料,研究了三种铝基原料(造粒氧化铝微粉、氧化铝空心微珠、六铝酸钙)对其常温抗折强度、高温抗折强度、抗热震性及抗氧化性的影响,并借助XRD和SEM对其物相组成及显微结构进行分析。结果表明,造粒氧化铝微粉是多孔结构,可吸收热应力,加入量为1%(质量分数,下同)时,可提高材料的常温抗折强度和抗热震性,明显改善材料的抗氧化性。氧化铝空心微珠是中空结构,可缓冲热应力,加入量为3%时,可明显提高材料的常温抗折强度,并具有较高的抗热震性和抗氧化性。六铝酸钙的热膨胀系数较低,可赋予材料较好的韧性,加入量不超过5%时,样品具有较好的抗热震性。     

Si-SiC复合粉添加量对低碳镁碳耐火材料性能的影响

为了综合利用在太阳能硅晶板生产过程中产生的大量工业废弃料Si-SiC复合粉,将其作为添加剂引入到镁碳砖中,研究了Si-SiC复合粉加入量(加入质量分数分别为0、1%、2%和3%)对低碳镁碳耐火材料性能的影响。结果表明,废弃Si-SiC复合粉可以提高低碳镁碳砖的抗氧化性与热处理后试样的常温力学性能。随Si-SiC复合粉添加量的提高,镁碳砖的抗氧化性提高。当添加量为2%(w)时,固化后试样及经1 600℃埋碳热处理后试样的力学性能最佳。综合考虑低碳镁碳砖的各项性能,Si-SiC复合粉的合适加入量为2%(w)。采用废弃Si-SiC复合粉作为低碳镁碳耐火材料的抗氧化剂可有效降低生产成本。     

氧化铝微粉加入量对特种硅莫砖性能的影响

以高铝矾土熟料、电熔白刚玉、碳化硅、广西白泥、氧化铝微粉为主要原料,亚硫酸纸浆废液为结合剂,制备出水泥窑过渡带用特种硅莫砖,研究了氧化铝微粉加入量对硅莫砖的常温物理性能、抗热震性和耐磨性的影响,并对试样进行XRD和SEM分析.结果表明:随着氧化铝微粉加入量的增加,硅莫砖的耐压强度、体积密度先升高后降低,显气孔率则先降低后升高;抗热震性随微粉加入量的增加先变好后边差的趋势;其中,微粉加入量为4％的硅莫砖综合性能最好,是大型水泥回转窑过渡带的理想内衬材料.     

硅粉加入量对转炉无水副枪用刚玉-莫来石浇注料性能的影响

为改善转炉无水副枪用浇注料的抗热震性,以质量分数分别为71%的板状刚玉、14%的烧结莫来石、3%的CA80水泥、2%的SiO_2微粉、10%的α-Al_2O_3微粉制备了刚玉-莫来石浇注料试样,研究了硅粉外加量(质量分数分别为0、1%、2%、3%、4%)对不同温度处理后试样性能的影响。结果表明:随着硅粉加入量增加,试样由收缩逐渐变为膨胀,试样的体积密度、常温抗折强度和常温耐压强度略有增加,显气孔率逐渐降低; 1 550℃处理后试样抗热震性能有所增加,且在硅粉加入量为2%(w)时试样的抗热震性最佳,强度保持率为48%。硅粉氧化为SiO_2后与Al_2O_3反应原位生成莫来石产生体积膨胀,在试样内部形成了一定量的微裂纹,提高了试样的抗热震性。     

热风炉管道用Al_2O_3-SiO_2浇注料性能的影响因素

为了提高热风炉管道用浇注料的使用寿命,以矾土均化料、红柱石颗粒和细粉、白刚玉细粉、纯铝酸钙水泥、SiO2微粉、α-Al2O3微粉、硅溶胶等为原料制备了热风炉管道用Al2O3-Si O2浇注料,并研究了SiO2微粉加入量、骨料类型、水泥加入量以及用硅溶胶作结合剂对浇注料性能的影响。结果表明:1)随着SiO2微粉加入量的增加,热处理后试样的常温抗折强度和常温耐压强度逐步增加,烧后收缩增大,体积密度先增加后降低,综合考虑,SiO2微粉的适宜加入量为4%(w);2)以矾土为骨料的试样具有较高的常温强度和较好的体积稳定性,但以红柱石为骨料时的抗热震性更好;3)结合系统含硅溶胶时,加入纯铝酸钙水泥能降低浇注料的烧后线变化,稍微提高常温强度和抗热震性,而加入柠檬酸则降低试样的抗热震性。     

电熔白刚玉细粉对RH炉用刚玉质浇注料性能的影响

为进一步提高RH炉用刚玉质浇注料的抗热震性,以烧结刚玉为骨料,烧结刚玉粉、活性氧化铝微粉和铝酸钙水泥(Secar 71)为基质,用电熔白刚玉粉替代基质中烧结刚玉粉,研究了电熔白刚玉加入量对RH炉浇注料1 600℃烧后体积密度、显气孔率、线变化、常温抗折强度、常温耐压强度以及抗热震性能的影响,并用SEM对试样进行显微结构分析。结果表明:随着电熔白刚玉粉加入量的增加,试样的体积密度、热震次数逐渐增加,显气孔率、线变化率逐渐减小,这与试样中生成的六铝酸钙量有关。当电熔白刚玉粉替代量为20%(w)时,试样的抗热震性最好。     

石墨加入量对低碳镁碳砖性能的影响

通过检测含有2%～14%石墨镁碳砖1400℃的高温抗折强度、1500℃的热膨胀系数、1000℃×2 h煅烧后的抗氧化性,比较低碳镁碳砖与传统镁砖的性能差异,研究了石墨加入量对低碳镁碳砖性能的影响。结果表明:在有2%Al存在的情况下,低碳镁碳砖高温抗折强度与石墨加入量无关;石墨加入量为6%时,可保证低碳镁碳砖具有较优良的抗剥落性及抗氧化性。     

钢包渣线用后镁碳砖的回收再利用研究

对钢包渣线用后镁碳砖进行回收处理,用其制备了再生渣线镁碳砖,研究了回收料加入量(质量分数分别为60%、70%、80%)和混料量(分别为5、8 kg)对再生镁碳砖致密度、强度和抗氧化性的影响。结果表明:1)随着回收料加入量的增加及混料量的增大,再生镁碳砖的显气孔率增大,体积密度、常温耐压强度、高温抗折强度和抗氧化性减小;2)回收料加入量(质量分数)为60%时,再生镁碳砖的性能符合行业标准的要求;3)回收料中存在假颗粒,残碳量高,杂质多,是造成再生镁碳砖致密度、强度和抗氧化性差的原因;4)为了提高再生镁碳砖的质量,必须控制回收料的加入量,选择混练效果好的混碾设备,并注意回收料中残碳对再生镁碳砖性能的影响。     

B4C-C复合粉体的合成及其在低碳镁碳砖中的应用

以炭黑和硼酸为原料,采用碳热还原法合成了部分石墨化B4C-C复合粉体,并将其作为碳源和抗氧化剂用于低碳镁碳砖中. 研究了加热温度对B4C-C复合粉体合成的影响,分析了其物相结构、成分、形貌和粒度. 通过测定低碳镁碳砖的常规物理性能、抗氧化性和热震稳定性,考察了复合粉体对低碳镁碳砖性能的影响. 结果表明,随加热温度升高,B4C-C复合粉体的石墨化度增大,B4C含量下降,1900℃时石墨化度达23.26%,B4C含量为20%左右,复合粉体中除部分微米、亚微米级的B4C外,85%以上为纳米级的B4C和部分石墨化炭黑. 添加复合粉体的低碳镁碳砖具有良好的常规物理性能、抗氧化性和热震稳定性.     

钢包渣线用超低碳MgO-MA-C砖的研制与应用

以高纯电熔镁砂、镁铝尖晶石微粉和纳米炭素为主要原料,分别加入总量为4%(质量分数)的硅粉、铝粉和硅粉-铝粉复合粉为防氧化剂,加入清洁的自来水混练均匀后,在500 t 摩擦压砖机上成型为碳质量分数小于1%的超低碳MgO-MA-C 标型砖试样.在对比各试样(包括普通MgO-C砖试样)的抗氧化性能、高温抗折强度、体积稳定性和抗渣性的基础上,对配方和生产工艺进行了优化,研制出了性能较好的超低碳(碳质量分数小于1%)MgO-MA-C砖.所研制砖在武钢200 t转炉钢包渣线区使用,平均使用次数达75次.     

金属铝结合镁-尖晶石-碳滑板的研制

研究了不同添加物(电熔刚玉、镁铝尖晶石、碳化硅和阿隆)对镁碳材料物理性能和抗热震性的影响,炭素种类对镁碳材料物理性能和抗氧化性的影响以及抗氧化剂种类和加入方式对镁碳材料常温抗折强度和抗氧化性的影响,根据确定的最佳添加物研制连铸钢包用滑板材料。结果表明:加入镁铝尖晶石有利于提高材料的抗热震性;与炭黑相比,添加597微细石墨可显著提高材料的常温抗折强度、致密度以及抗氧化性;以碳化硼和硅粉作为复合添加剂,有利于提高材料中、高温处理后的常温抗折强度,同时也提高了材料的抗氧化性;研制的镁-尖晶石-碳滑板材料在实际使用中的抗拉毛性优于重烧铝锆碳滑板,达到了钢厂的使用要求。     

The Effect of Graphite Particle Size on Properties of Low Carbon MgO-C Composite Materials

The effects of graphite granularity on the properties of low carbon MgO-C based materials have been investigated in the work. Large crystal fused magnesia, natural flake graphite with different particle sizes and anti-oxidant were adopted as raw material for preparation of specimens. However, the results show that the physical properties oxidation resistance and thermal shock resistance of low carbon MgO-C materials with content of 4.0 wt% graphite are improved obviously through the use of special and suitable size graphite. The excellent performance achieved was considered as a result of microstructure modification of MgO-C materials. Therefore, it is suggested that both fine and micro grade natural flake graphite used for production of low carbon MgO-C bricks.     

Improvement of low carbon MgO-C refractories by MA-CA2 additives fabricated from metallurgical waste

In the present work, MA-CA₂ material was fabricated by adding industrial alumina into industrial waste residue, and its effect on the physical properties, oxidation resistance, slag resistance, and thermal shock resistance when it was added to the composition of a low carbon MgO-C refractory was discussed in detail. Although the introduction of MA-CA₂ material led to a slight inferior slag corrosion resistance, the volume stability and oxidation resistance of refractories were improved. Moreover, the samples containing MA-CA₂ addition showed significantly lower thermal expansion coefficients and increased thermal shock resistance performance. However, owing to the dissolution of SiO₂ impurity into the MA-CA₂ material, an excessive addition of MA-CA₂ material would increase the liquid phase amount in the sample during the heat treatment and slag attack, resulting in a performance degradation. In this study, the best comprehensive performance of the MgO-C refractory was obtained with 6 wt% MA-CA₂ addition.     

Effect of Ti （C,N） on Properties of Low-carbon MgO- C Bricks

The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XRD and SEM analysis together with EDS. The results showed that Ti （ C, N） distributed in the matrix of lowcarbon MgO - C brick uniformly after being treated at 1 600 ~C for 3 h in coke powder bed, and Ti （C, N） and MgO formed a solid solution. After the treatment at 1 600 ℃ for 3 h in coke powder bed, the bulk density and cold crushing strength of low-carbon MgO - C brick with Ti （ C, N） decreased, and the apparent porosity and linear change rate of specimens increased. The oxidation resistance of low-carbon MgO - C brick with Ti（ C, N） was superior to that of low-carbon MgO - C brick with no additives, but inferior to that of low-car- bon MgO - C brick with Al powder. The slag resistance of the specimen with Ti （ C, N） was excellent as well.     

Performance of a ceramic frit anti-oxidation coating on a MgO-C refractory brick

In steel production, ladles must be preheated to minimize the heat loss of the steel melt, prevent thermal shock of refractory bricks (MgO-C), and to maximize the lining life of ladle. Partial oxidation of MgO-C bricks begins in the graphite bond during the preheating. Oxidation of graphite bond also causes a decrease in performance of the bricks because of an increase in the brick porosity. In this article, coating on a MgO-C brick surface by a ceramic film to protect against carbon oxidation was studied. Coated and un-coated bricks were heated at 1200 °C, cooled to room temperature, then the brick properties investigated. The oxidization resistance properties of brick with coating were much better than those without coating, which should lead to longer refractory service life.     

Improvement of Durability of Purging Plugs Using MgO Micropowder for Refining Ladles

To modulate the matrix of purging plugs, MgO micropowder was introduced as a replacement to magnesia powder in alumina–magnesia castables, and the effect of MgO micropowder on the properties of alumina–magnesia castables and the possibility of developing chrome‐free castables were investigated. Experimental results showed that the introduction of MgO micropowder resulted in an improvement in the volume stability, strength, and thermal shock resistance of alumina–magnesia castables due to its high surface energy and small particle size. However, excessive amounts of MgO micropowder led to a lower densification, and there was a slight degradation in the performance of the alumina–magnesia castables. The slag resistance of the prepared alumina–magnesia castables was significantly better than that of the alumina–chrome castables. Microstructure and energy spectrum analysis showed that the formation of a solidified reaction layer, mainly consisting of spinel and CaAl₁₂O₁₉, was the major cause of the observed difference in slag resistance. In addition, the alumina–magnesia castables had a lower linear thermal expansion coefficient than that of the alumina–chrome castables at each experimental temperature, which effectively decreased the thermal stress during its service period, thus exhibiting good thermal shock resistance.     

低碳MgO-C材料的抗热震性研究

以电熔大结晶镁砂、天然鳞片石墨、纳米炭黑、酚醛树脂、铝粉等为主要原料制备w(C)=3%的低碳MgO-C材料,以其抗热震性为考核指标,选取颗粒级配、复合抗氧化剂、石墨粒度和复合结合剂4个因素,进行了四因素三水平正交试验。结果表明:在本试验范围内,颗粒级配是影响低碳MgO-C材料抗热震性的主要因素,复合抗氧化剂次之,石墨粒度和复合结合剂的影响基本相当;通过极差分析确定,镁砂颗粒级配(3～1、1～0.088和≤0.088mm的镁砂的质量比)采用50:23:27,复合抗氧化剂采用Al2.5+Mg-Al0.5+B4C0.5,石墨粒度采用10μm的,复合结合剂采用炭黑N220+沥青+酚醛树脂,可制备出抗热震性最佳的低碳MgO-C材料。